Storage wrap material

ABSTRACT

The present invention relates to an improved storage wrap material comprising a sheet of material comprising one or more layers, and having a first, active side and a second side, said sheet comprising a plurality of standoffs at a density of greater than about 200 standoffs per square inch; and an adhesive; wherein the standoffs are selected from the group consisting of deformable standoffs, removable standoffs, repositionable standoffs, frangible standoffs, or mixtures thereof; and wherein the storage wrap material is linerless and consists of no reinforcing or supporting elements.

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application is a continuation of commonly-assigned, U.S.patent application Ser. No. 09/715,586, filed Nov. 17, 2000, which is acontinuation of U.S. patent application Ser. No. 08/745,340, filed Nov.8, 1996, issued as U.S. Pat. No. 6,194,062, which is acontinuation-in-part of U.S. patent application Ser. No. 08/584,638,filed Jan. 10, 1996, issued as U.S. Pat. No. 5,662,758.

FIELD OF THE INVENTION

[0002] The present invention relates to sheet-like materials suitablefor use in the containment and protection of various items, as well asthe preservation of perishable materials such as food items. The presentinvention further relates to such materials which are suitable fordirect contact with such items as a unitary package as well as for usein forming a closure for a semi-enclosed container.

BACKGROUND OF THE INVENTION

[0003] Sheet-like materials for use in the containment and protection ofvarious items, as well as the preservation of perishable materials suchas food items, are well known in the art. Such materials can be utilizedto wrap items individually and/or can be utilized to form a closure fora semi-enclosed container.

[0004] One class of such materials in common use today comprises thoseof polymeric composition formed into a thin, conformable web commonlysupplied in rolled form. Common examples of such materials are polyvinylchloride (PVC), polyvinylidene chloride (PVDC), and polyethylene (PE)sheet materials. These materials exhibit a clinging character on atleast one surface due to the properties of the polymeric materials theyare formed from and/or additives such as plasticizers, tackifiers, etc.,such that they may be folded or wrapped around an item such that theycling to the item and/or to themselves. The clinging character of suchmaterials also permits their use in combination with semi-enclosedrigid, semi-rigid, or flexible containers to provide a fully enclosedcontainer structure. The barrier properties of many such materials,particularly their oxygen, moisture/moisture vapor, and odor barrierproperties, provide the desired preservation characteristics forperishable items such as food items and/or items which oxidize orotherwise degrade more rapidly with continued exposure to environmentalconditions.

[0005] While these materials have achieved a certain level ofacceptance, where the material is supplied in the form of a continuousroll in a dispensing carton or apparatus, difficulty is oftenencountered locating and isolating the current end portion of the rolledweb in order to start the dispensing operation. In order to address thisissue, a number of methods of identifying and/or isolating the currentend of the rolled web have been developed (tabs, colors, end-graspingdispenser features, etc.) which have achieved varying levels of success.Irregardless of the issue of handling the end of the rolled web, thetendency of the material to cling to itself also increases thedispensing force required to unroll the web and tangentially separatethe dispensed portion and, if excessive, can lead to a phenomenon knownas “roll blocking” wherein the dispensing force to unroll becomesexcessive. Roll blocking can also cause excessive dispensing forceswhich can lead to longitudinal tearing of the web in the roll direction,leading the user to dispense a narrower, unevenly-torn portion of therolled web. In addition, users frequently encounter situations whereinthe material clings to itself prematurely (i.e., before contacting thedesired bonding surface), thus necessitating either the manualdisengagement of the clinging portion(s) and/or discarding of thematerial in favor of a new portion.

[0006] Another difficulty which may be encountered is the failure of thematerial to adhere to itself and/or the desired target surfacesufficiently to form an airtight seal either from the outset or after aperiod of handling of the container or wrapped item. If such materialscannot form a seal with barrier properties at least as great as those ofthe material itself, the full potential of such materials in use as astorage wrap cannot be realized as the seal becomes the weakest link interms of containerization. Accordingly, some users employ additionalsecurement features such as rubber bands, tapes, etc. Wrinkles in thematerial where it clings to itself or a target surface can leave smallchannels in the region between the material and the opposing surface,thereby causing a failure to achieve the desired seal quality forpreservation of perishable items. Some users attempt to address sealquality shortcomings by double- or triple-wrapping the desired item toform a tortuous labyrinth seal path of increased length.

[0007] Also, because the materials “cling” to themselves and othersurfaces, i.e., exhibit an attraction or affinity for the materialrather than an adhesive bond, their affinity for a complementary surfaceis highly dependent upon material characteristics such as chemicalcomposition, electrical conductivity, surface energy, surface finish,etc. Therefore, such materials leave room for improvement both in easeof use as well as ability to form an adequate seal for preservation ofperishable items. In many instances, the plasticizers, tackifiers, andother cling additives utilized to provide the cling properties of suchmaterials may also introduce undesirable attributes such as odor to thefinished web and/or may introduce environmental concerns.

[0008] Another class of materials in common use today comprises thin,conformable webs of various compositions commonly supplied in individualsheet or rolled form. Common examples of such materials include aluminumfoil, coated (waxed, etc.) paper, etc. These materials exhibit noadhesive or cling character on either surface, instead relying upon thedead-fold characteristics of the materials they are formed from suchthat they may be folded or wrapped around an item and retain theirfolded or wrapped shape. The ability of these materials to maintaintheir folded or creased shape also permits their use in combination withsemi-enclosed rigid, semi-rigid, or flexible containers to provide afully enclosed container structure. The barrier properties of many suchmaterials, particularly their oxygen, moisture/moisture vapor, and odorbarrier properties, provide the desired preservation characteristics forperishable items such as food items and/or items which oxidize orotherwise degrade more rapidly with continued exposure to environmentalconditions.

[0009] While these materials have achieved a certain level ofacceptance, users frequently encounter situations wherein the materialfails to remain sufficiently folded and engaged with itself and/or asemi-enclosed container to adequately enclose and preserve the item(i.e., the folds tend to unfold with time or mechanical disturbance),thus necessitating either refolding and external securement of thefolded portion(s) and/or discarding of the material in favor of a newportion and re-accomplishing the wrapping process. In some instances,such materials may also be constructed of very thin materials in orderto achieve the desired degree of conformability. This may result in thematerial having insufficient tensile properties to dispense from a rollwithout longitudinal tearing of the web in the roll direction, leadingthe user to dispense a narrower, unevenly-torn portion of the rolledweb.

[0010] Another difficulty which may be encountered is the failure of thematerial to form an adequate seal where folded either from the outset orafter a period of handling of the container or wrapped item. If suchmaterials cannot form a seal with barrier properties at least as greatas those of the material itself, the full potential of such materials inuse as a storage wrap cannot be realized as the seal becomes the weakestlink in terms of containerization. Accordingly, some users undertake toemploy additional securement features such as rubber bands, tapes, etc.Wrinkles in the material where it meets itself or a target surface canleave small channels in the region between the material and the opposingsurface, thereby causing a failure to achieve the desired seal qualityfor preservation of perishable items. Some users attempt to address sealquality shortcomings by double- or triple-wrapping the desired item toform a tortuous labyrinth seal path of increased length.

[0011] The effective fold radius of these materials is also a factor indetermining their suitability for forming an effective seal, as the foldradius of some materials (paper based, etc.) is determined by suchmaterial properties as fiber length. A fold radius which is too largewill generally render such a material unsuitable for forming aneffective seal. In addition, due to the fact that most such dead-foldtype materials are opaque, the condition and/or type of items containedin such a packaging system are also obscured from view, necessitatingun-wrapping and re-wrapping the items to permit inspection.

[0012] Such materials, due to their lack of any adhesive properties, arealso difficult to effectively employ in the preservation of perishableitems in combination with a semi-enclosed container where the containerprovides no physical or mechanical engagement features (such as aconventional bowl) around which to fold the material to effect amechanical labyrinth-type seal between the material and the container.Therefore, such materials leave room for improvement both in ease of useas well as ability to form an adequate seal for preservation ofperishable items.

[0013] Accordingly, it would be desirable to provide an improved storagewrap material which exhibits convenient, efficient dispensing by a userby having a readily located end portion and a comparatively lowunrolling force.

[0014] It would also be desirable to provide such a material which iseasily handled and manipulated by a user during the enclosure processyet forms an adequate seal with a wide variety of materials and surfacesto effectively preserve perishable items.

[0015] It would also be desirable to provide such a material which iscapable of being utilized in various modes of item containment andpreservation as desired by a user, such as independent use and/or use incombination with a semi-enclosed container, in efficient fashion bysubstantially reducing if not eliminating the need for double-wrappingand/or additional securement features.

[0016] It would further be desirable to provide such materials which arecapable of being readily manufactured, stored, and re-used as desirablefor both economic and environmental efficiency.

SUMMARY OF THE INVENTION

[0017] The present invention provides an improved storage wrap materialcomprising a sheet of material having a first side and a second side.The first side comprises an active side exhibiting an adhesion peelforce after activation by a user which is greater than an adhesion peelforce exhibited prior to activation by a user.

[0018] The storage wrap material may be activated by differentapproaches, but in a preferred embodiment the active side is activatibleby an externally applied force exerted upon the sheet of material. Theforce may be an externally applied compressive force exerted in adirection substantially normal to the sheet of material or may be anexternally applied tensile force exerted in a direction substantiallyparallel to the sheet of material.

[0019] The active side of the storage wrap material preferably exhibitsan adhesion peel force of at least about 1 ounce per linear inch, morepreferably between about 1 and about 2.5 ounces per linear inch, afteractivation by a user. In accordance with the present invention, thestorage wrap material is selectively activatible by a user in discreteregions to provide adhesive properties where and when desired. The useof an adhesive or adhesive-like substance on the surface of the materialprovides an adhesion peel force after activation which is sufficient toform a barrier seal against a target surface at least as great as thoseof the material and the target surface such that perishable items, suchas food items, may be effectively preserved.

[0020] The storage wrap materials of the present invention may beutilized to enclose and protect a wide variety of items by variousmethods of application, including direct application to the desireditem, enclosure of the desired item and securement to itself, and/or incombination with a semi-enclosed container.

[0021] Such storage wrap materials of the present invention may beadvantageously employed in a container system comprising, incombination, the storage wrap material and a semi-enclosed containerwith at least one opening surrounded by a peripheral edge. The storagewrap material is adhered to the peripheral edge over the openingfollowing activation by a user to convert the semi-enclosed container toa closed container.

BRIEF DESCRIPTION OF THE DRAWINGS

[0022] While the specification concludes with claims particularlypointing out and distinctly claiming the present invention, it isbelieved that the present invention will be better understood from thefollowing description in conjunction with the accompanying DrawingFigures, in which like reference numerals identify like elements, andwherein:

[0023]FIG. 1 is a perspective view of the storage wrap material of thepresent invention provided in roll form;

[0024]FIG. 2 is a plan view of a preferred embodiment of athree-dimensional, nesting-resistant sheet material suitable for use asa storage wrap material in accordance with the present invention;

[0025]FIG. 3 is a partial elevational sectional view of the sheetmaterial of FIG. 2, wherein a substance is included within thethree-dimensional structure of the web;

[0026]FIG. 4 is a plan view of a three-dimensional forming structuresuitable for forming a three-dimensional, nesting resistant sheetmaterial such as that of FIG. 3;

[0027]FIG. 5 is a partial elevational sectional view of thethree-dimensional forming structure of FIG. 4;

[0028]FIG. 6 is a schematic illustration of a representative apparatussuitable for forming a storage wrap material in accordance with thepresent invention;

[0029]FIG. 7 is a perspective view of the storage wrap material of thepresent invention being formed into a unitary package around an item tobe stored by bonding the material to itself around the item;

[0030]FIG. 8 is a perspective view of the storage wrap material of thepresent invention being utilized in combination with a semi-enclosedcontainer to form a closed container; and

[0031]FIG. 9 is a perspective view of the storage wrap material of thepresent invention being formed into a unitary package around an item tobe stored by bonding overlying portions of the material to itself overthe item.

DETAILED DESCRIPTION OF THE INVENTION

[0032]FIG. 1 depicts a preferred embodiment of a storage wrap material10 according to the present invention. As shown in FIG. 1, storage wrapmaterial 10 is preferably provided in the form of a web of flexiblematerial which can be wound upon a core to form a roll 20 which issuitable for use in a dispenser or holder such as carton 30. If desired,perforations may be provided to facilitate dispensing of pre-measureddimensions of the material in the event that the dispenser, holder, orcontainer does not include a suitable severing apparatus. Manualsevering with sharp implements such as knives and scissors may also beaccomplished in order to utilize the material in continuousnon-perforated form. In alternative storage and dispensingconfigurations, the storage wrap material may be provided in the form ofdiscrete, pre-measured sheets of uniform or non-uniform dimensions whichmay be stacked upon one another in any desired sequence and/ororientation and dispensed from a carton, bag, or any other suitabledispensing apparatus. In another alternative storage and dispensingconfiguration, the storage wrap material may be provided in the form ofa continuous web which is Z-folded or pleated and placed in a dispensingcarton.

[0033] In accordance with the present invention, storage wrap material10 exhibits minimal, and preferably no, adhesive or cling propertiesuntil activated by a user. This characteristic permits storage wrap 10to be stored and dispensed in any desired mode without encountering thedifficulties of premature clinging or adhering to itself, and withoutthe need for separate release sheets, liners, spacers, or the like. Atthe same time, when activated at the desired location and at the desiredtime, the storage wrap material exhibits sufficient adhesive propertiesto form a bond to most common materials which is sufficiently strong soas to survive handling without failure. The bond between the storagewrap material and a target surface is also sufficient to provide abarrier seal against transmission of oxygen, moisture/moisture vapor,odor, etc. such that perishable items may be satisfactorily enclosed andpreserved to the extent of the barrier properties of the materialitself.

[0034] Although storage wrap material may be provided with two activesides or surfaces, if desired for particular applications, in accordancewith the present invention it is presently preferred to provide storagewrap material with only one active side and one inactive or inert side.

[0035] The active side of the storage wrap material may be selectivelyactivated by a user to provide activated regions where desired toprovide selective adhesion of the material to a target surface. Thetarget surface may comprise a separate surface or material, such as acontainer or an item or items to be wrapped, or may comprise anotherportion of the storage wrap material itself. Selective activationresults in the generation of only so much active area with adhesiveproperties as is needed, i.e., all remaining portions of the storagewrap material remain inactive or inert. The storage wrap material istherefore capable of forming discrete inactive and active regions on thesame side of the material in addition to the ability to have an activeside and an inactive side.

[0036] Various means of activation are envisioned as being within thescope of the present invention, such as compression, extension, thermalactivation, etc. However, in terms of providing the user with thedesired degree of control over the activation process the compressionactivation method is presently preferred.

[0037] Regardless of the manner of activation, storage wrap materials ofthe present invention will exhibit an adhesive, adherent, or tackingcharacter as opposed to merely a clinging or affinity character.Accordingly, such storage wrap materials will form a bond or seal whenin contact with itself or another target surface as opposed to merelybeing attracted to such surface. While a number of approaches such asthe use of selectively adherent materials may be utilized to provide thedesired adhesive properties, a presently preferred approach is toutilize a pressure-sensitive adhesive. When designing storage wrapmaterials in accordance with the present invention, it may be desirableto tailor the particular choice of adhesive agent so as to provideeither a permanent bond or a releasable bond as desired for a particularapplication. Where a permanent bond is desired, opening of the wrap orenclosed container for access to the item(s) therein requiresdestruction of the storage wrap and/or the container. Releasable bonds,on the other hand, provide access to the wrapped item(s) by permittingseparation of the wrap from itself or the container at the bond sitewithout destruction. Moreover, depending upon the activation mechanismemployed in the design of the storage wrap material, the releasable bondmay additionally be refastenable if sufficient adhesive characterremains after the initial activation/bonding/release cycle.

[0038] Several physical characteristics or properties are believed to beimportant in the design and construction of a suitable storage wrapmaterial in accordance with the present invention.

[0039] In order to accommodate a wide range of items to bewrapped/packaged in terms of shape and size, as well as a wide range ofcontainer shapes when utilized in combination with a semi-enclosedcontainer, the storage wrap material is preferably sufficiently flexibleto conform readily to any desired surface. At the same time, the memoryor resiliency of the material must be sufficiently small that it doesnot exert undue restorative forces which would tend to cause thematerial to break contact with the container/item/target surface andthus become prematurely unsecured or unsealed over time. While design ofthe storage wrap material for the intended application will require abalancing of the various physical properties, as a general propositionit is presently preferred for a wide variety of applications to select amaterial having greater plasticity than elasticity.

[0040] Another property which has been found to be important indesigning storage wrap materials in accordance with the presentinvention is the degree of adhesion that they exhibit after activationby a user. More particularly, the storage wrap materials of the presentinvention exhibit an adhesion sufficient to survive the likely degree ofhandling the wrapped item or enclosed container is likely to encounterin use while maintaining the desired level of sealing engagement withthe item, with itself, or with the accompanying semi-enclosed containersuch that preservation of perishable items is ensured.

[0041] One way to measure or quantify this adhesion property is in termsof an adhesion peel force value which is preferably measured by PressureSensitive Tape Council Method PSTC-1. A 12 inch (30.5 cm) long by 1 inch(2.5 cm) wide strip of film is rolled once against a smooth stainlesssteel surface at a rate of 12 inches (30.5 cm) per minute using a 4.5pound (2.04 kg) roller and then tested as having a peak adhesion peelforce value ranging from about 1 to about 50 ounces/inch (0.012 to 0.600kg/cm), more preferably from about 1 to about 2.5 ounces/inch (0.012 to0.027 kg/cm) of strip width. In general, minimum adhesion whichmaintains a seal is desired for a storage wrap, so that the wrap iseasily peeled open for access to the stored item(s).

[0042] In a preferred embodiment, the improved storage wrap material ofthe present invention is a substantially clingless wrap material incontrast to typical commercially-available storage wrap materials. Asdiscussed above, such materials exhibit “cling” properties on a constantbasis, such that they cling to themselves and to other surfaces wheneverbrought into proximity with them, whether desirable or not. Suchmaterials often incorporate resins, additives, tackifiers, or othermaterials to achieve the target level of cling. Suitable methods ofmeasuring and quantifying this cling property are described in ASTM testmethods D5458-95 and D3354-89. Test method D5458-95 is useful formeasuring cling between two layers of film in both stretched andunstretched conditions, and utilizes a 1 inch wide film strip adhered toa flat film attached to an inclined surface. The force required toremove the film strip from the flat film is measured. Test methodD3354-89 is useful for measuring the degree of blocking (unwantedadhesion) existing between overlapping layers of plastic film.Film-to-film adhesion is expressed as a blocking load in grams whichwill cause two layers of polyethylene film to separate with an area ofcontact of 100 square centimeters.

[0043] Substantially clingless wrap materials in accordance with thepresent invention can be produced by proper selection of materialsincluding the avoidance of any significant amount of materials known inthe art as “cling additives”, including those of the types describedabove. Further, additional materials or additives can be incorporated asneeded to further reduce, if not eliminate, the tendency of suchmaterials to cling to themselves and other surfaces. Such materialswould include anti-static agents, etc.

[0044] The improved storage wrap materials of the present invention maytake many forms and may be manufactured by a variety of differentapproaches. One design category that can provide the required propertiesincorporates the use of standoffs to prevent an adhesive layer frommaking contact with external surfaces before intended to do so. Throughuser activation, the standoffs are designed to be deformable, removable,repositionable, or frangible in order to expose the adhesive, whenintended, to the target surface. One particular approach within thatdesign category which is believed to be presently preferred is to form athree-dimensional polymeric film structure with a layer ofpressure-sensitive adhesive protected from contact with other surfacesby integrally-formed deformable protrusions or stand-offs. To activatethe material, once the material is positioned over the desired targetsurface (which may be another portion of itself) the user exerts apressure on the desired location of the material to collapse theprotrusions and bring the adhesive into engagement with the targetsurface to form the desired bond. Such materials are described ingreater detail in U.S. Pat. No. 5,662,578, issued to Hamilton et al. onSep. 2, 1997, hereby incorporated herein by reference.

[0045] If such a three-dimensional structure is used as a storage wrapin accordance with the present invention, for example, the externalcontact surfaces may be either compliant or rigid and planar ornon-planar. Having the three dimensional structure deform is preferredfor use with a rigid target surface. If the substance is adhesive andthe objective is releasable adherence to a target surface afterdeformation of the structure, then degree of adhesion is important.Inversion of protrusions, especially those made of HDPE, minimizesprotrusion spring back so that higher adhesion isn't necessary in orderto prevent the failure of relatively weak seals. In this embodiment itis desired that the protrusion remain “dead” or non-resilient afterbeing inverted or crushed; however, a resilient protrusion could beused, for example, where it is intended for the bond to be permanent,where aggressive adhesive overcomes spring back. Also, a resilientprotrusion may be desirable where repeat use of the material isintended.

[0046] FIGS. 2-3 illustrates a typical storage wrap material 10constructed in accordance with the aforementioned Hamilton et al.application which is suitable for use as a storage wrap material of thepresent invention. In a preferred embodiment, the three-dimensionalprotrusions depicted in FIGS. 2-3 may be formed in an amorphous patternof two-dimensional geometrical shapes such that the sheet of materialresists nesting of superimposed layers such as would be encountered in aroll of product. Such three-dimensional, nesting-resistant materials andpatterns are described in greater detail in commonly-assigned,co-pending, concurrently-filed U.S. Pat. No. 5,965,235, issued toKenneth S. McGuire et al. on Oct. 12, 1999, hereby incorporated hereinby reference.

[0047] When the material is formed into an elongated web with theintention of winding it upon a mandrel or upon itself (core-less roll)for purposes of compact storage, in accordance with the presentinvention the web exhibits the non-uniform pattern at least in thedirection of rolling, and most preferably in both the rolling directionand the cross-rolling direction. While an infinitely non-repeatingpattern may be desirable for certain applications, at a minimum thematerials of the present invention will exhibit a non-uniform patternproperty for a web distance at least as great as the maximum intendedroll circumference of a roll of product.

[0048] In order to provide the greatest degree of nesting-resistance,the three-dimensional, nesting-resistant sheet materials of the presentinvention preferably exhibit a two-dimensional pattern ofthree-dimensional protrusions which is substantially amorphous innature. As utilized herein, the term “amorphous” refers to a patternwhich exhibits no readily perceptible organization, regularity, ororientation of constituent elements. This definition of the term“amorphous” is generally in accordance with the ordinary meaning of theterm as evidenced by the corresponding definition in Webster's Ninth NewCollegiate Dictionary. In such a pattern, the orientation andarrangement of one element with regard to a neighboring element bear nopredictable relationship to that of the next succeeding element(s)beyond.

[0049] By way of contrast, the term “array” is utilized herein to referto patterns of constituent elements which exhibit a regular, orderedgrouping or arrangement. This definition of the term “array” is likewisegenerally in accordance with the ordinary meaning of the term asevidenced by the corresponding definition in Webster's Ninth NewCollegiate Dictionary. In such an array pattern, the orientation andarrangement of one element with regard to a neighboring element bear apredictable relationship to that of the next succeeding element(s)beyond.

[0050] The degree to which order is present in an array pattern ofthree-dimensional protrusions bears a direct relationship to the degreeof nestability exhibited by the web. For example, in a highly-orderedarray pattern of uniformly-sized and shaped hollow protrusions in aclose-packed hexagonal array, each protrusion is literally a repeat ofany other protrusion. Nesting of regions of such a web, if not in factthe entire web, can be achieved with a web alignment shift betweensuperimposed webs or web portions of no more than one protrusion-spacingin any given direction. Lesser degrees of order may demonstrate lessnesting tendency, although any degree of order is believed to providesome degree of nestability. Accordingly, an amorphous, non-orderedpattern of protrusions would therefore exhibit the greatest possibledegree of nesting-resistance.

[0051] While it is presently preferred that the entire surface of a webin accordance with the present invention exhibit such an amorphouspattern, under some circumstances it may be desirable for less than theentire surface of such a web to exhibit such a pattern. For example, acomparatively small portion of the web may exhibit some regular patternof protrusions or may in fact be free of protrusions so as to present agenerally planar surface. In addition, wherein the sheet material is tobe formed as a comparatively large sheet of material and/or as anelongated continuous web to be folded or wound upon itself,manufacturing constraints may require that the amorphous pattern itselfbe repeated periodically within the web. Although any pattern repetitionwithin the web allows some possibility of nesting occurring, such apossibility only exists when precise alignment of superimposed webs orweb portions occurs with such webs or web portions representing exactlyone repeat of the pattern (or an integer number of repeats for acontinuous wound or folded web). This contrasts with the nestingcharacter of webs formed of uniformly-shaped protrusions in an arraypattern wherein each protrusion is a repeat of the adjacent protrusionssuch that the repeat distance is a single protrusion spacing. In such aconfiguration, alignment for nesting would occur if web alignment occurswith a shift of no more than one protrusion-spacing.

[0052] In a web with an amorphous pattern of three-dimensionalprotrusions, any selection of an adjacent plurality of protrusions willbe unique within the scope of the pattern, even though under somecircumstances it is conceivable that a given individual protrusion maypossibly not be unique within the scope of the pattern. By utilizing anamorphous pattern, the three-dimensional sheet of material (in the caseof a sheet having hollow, three-dimensional protrusions) will not nestunless precise superposition of sheets of material having the sameamorphous pattern occurs.

[0053] Three-dimensional sheet materials having a two-dimensionalpattern of three-dimensional protrusions which is substantiallyamorphous in nature are also believed to exhibit “isomorphism”. Asutilized herein, the terms “isomorphism” and its root “isomorphic” areutilized to refer to substantial uniformity in geometrical andstructural properties for a given circumscribed area wherever such anarea is delineated within the pattern. This definition of the term“isomorphic” is generally in accordance with the ordinary meaning of theterm as evidenced by the corresponding definition in Webster's Ninth NewCollegiate Dictionary. By way of example, a prescribed area comprising astatistically-significant number of protrusions with regard to theentire amorphous pattern would yield statistically substantiallyequivalent values for such web properties as protrusion area, numberdensity of protrusions, total protrusion wall length, etc. Such acorrelation is believed desirable with respect to physical, structuralweb properties when uniformity is desired across the web surface, andparticularly so with regard to web properties measured normal to theplane of the web such as crush-resistance of protrusions, etc.

[0054] Utilization of an amorphous pattern of three-dimensionalprotrusions has other advantages as well. For example, it has beenobserved that three-dimensional sheet materials formed from a materialwhich is initially isotropic within the plane of the material remaingenerally isotropic with respect to physical web properties indirections within the plane of the material. As utilized herein, theterm “isotropic” is utilized to refer to web properties which areexhibited to substantially equal degrees in all directions within theplane of the material. This definition of the term “isotropic” islikewise generally in accordance with the ordinary meaning of the termas evidenced by the corresponding definition in Webster's Ninth NewCollegiate Dictionary. Without wishing to be bound by theory, this ispresently believed to be due to the non-ordered, non-orientedarrangement of the three-dimensional protrusions within the amorphouspattern. Conversely, directional web materials exhibiting web propertieswhich vary by web direction will typically exhibit such properties insimilar fashion following the introduction of the amorphous pattern uponthe material. By way of example, such a sheet of material could exhibitsubstantially uniform tensile properties in any direction within theplane of the material if the starting material was isotropic in tensileproperties.

[0055] Such an amorphous pattern in the physical sense translates into astatistically equivalent number of protrusions per unit length measureencountered by a line drawn in any given direction outwardly as a rayfrom any given point within the pattern. Other statistically equivalentparameters could include number of protrusion walls, average protrusionarea, average total space between protrusions, etc. Statisticalequivalence in terms of structural geometrical features with regard todirections in the plane of the web is believed to translate intostatistical equivalence in terms of directional web properties.

[0056] Revisiting the array concept to highlight the distinction betweenarrays and amorphous patterns, since an array is by definition “ordered”in the physical sense it would exhibit some regularity in the size,shape, spacing, and/or orientation of protrusions. Accordingly, a lineor ray drawn from a given point in the pattern would yield statisticallydifferent values depending upon the direction in which the ray extendsfor such parameters as number of protrusion walls, average protrusionarea, average total space between protrusions, etc. with a correspondingvariation in directional web properties.

[0057] Within the preferred amorphous pattern, protrusions willpreferably be non-uniform with regard to their size, shape, orientationwith respect to the web, and spacing between adjacent protrusioncenters. Without wishing to be bound by theory, differences incenter-to-center spacing of adjacent protrusions are believed to play animportant role in reducing the likelihood of nesting occurring in theface-to-back nesting scenario. Differences in center-to-center spacingof protrusions within the pattern result in the physical sense in thespaces between protrusions being located in different spatial locationswith respect to the overall web. Accordingly, the likelihood of a“match” occurring between superimposed portions of one or more webs interms of protrusions/space locations is quite low. Further, thelikelihood of a “match” occurring between a plurality of adjacentprotrusions/spaces on superimposed webs or web portions is even lowerdue to the amorphous nature of the protrusion pattern.

[0058] In a completely amorphous pattern, as would be presentlypreferred, the center-to-center spacing is random, at least within adesigner-specified bounded range, such that there is an equal likelihoodof the nearest neighbor to a given protrusion occurring at any givenangular position within the plane of the web. Other physical geometricalcharacteristics of the web are also preferably random, or at leastnon-uniform, within the boundary conditions of the pattern, such as thenumber of sides of the protrusions, angles included within eachprotrusion, size of the protrusions, etc. However, while it is possibleand in some circumstances desirable to have the spacing between adjacentprotrusions be non-uniform and/or random, the selection of polygonshapes which are capable of interlocking together makes a uniformspacing between adjacent protrusions possible. This is particularlyuseful for some applications of the three-dimensional, nesting-resistantsheet materials of the present invention, as will be discussedhereafter.

[0059] A sheet or web of material can be intentionally created with aplurality of amorphous areas within the same sheet or web, even to thepoint of replication of the same amorphous pattern in two or more suchregions. The designer may purposely separate amorphous regions with aregular defined, non-amorphous pattern or array, or even a “blank”region with no protrusions at all, or any combination thereof. Theformations contained within a non-amorphous area can be of any numberdensity, height or shape. Further, the shape and dimensions of thenon-amorphous region itself can be customized as desired. Additionalexamples of formation shapes, but not intended to be exhaustive, are:wedges emanating from a point; truncated wedges; polygons; circles;curvilinear shapes; or combinations thereof.

[0060] Additionally, a single amorphous region may fully envelop orcircumscribe one or more non-amorphous areas. An example is a single,continuous amorphous region with non-amorphous patterns fully enclosednear the center of the sheet or web. Such imbedded patterns maycommunicate brand name, the manufacturer, instructions, material side orface indication, other information or simply be decorative in nature.

[0061] Multiple non-amorphous regions may be abutted or overlapped in asubstantially contiguous manner to substantially divide one amorphouspattern into multiple regions or to separate multiple amorphous regionsthat were never part of a greater single amorphous region beforehand.

[0062] From the foregoing discussion it would be apparent that theutilization of an amorphous pattern of three-dimensional protrusionsenables the fabrication of webs having the advantages of an arraypattern, for example, statistical uniformity in web properties on anarea/location basis, without the key disadvantages of using an array insuch applications, namely nestability and anisotropism.

[0063] Webs according to the present invention may have protrusionsformed of virtually any three-dimensional shape, and accordingly neednot be all of a convex polygonal shape. However, it is presentlypreferred to form the protrusions in the shape ofsubstantially-equal-height frustums having convex polygonal bases in theplane of one surface of the material and having interlocking, adjacentparallel sidewalls. For other applications, however, the protrusionsneed not necessarily be of polygonal shape.

[0064] As used herein, the term “polygon” (and the adjective form“polygonal”) is utilized to refer to a two-dimensional geometricalfigure with three or more sides, since a polygon with one or two sideswould define a line. Accordingly, triangles, quadrilaterals, pentagons,hexagons, etc. are included within the term “polygon”, as wouldcurvilinear shapes such as circles, ellipses, etc. which would have aninfinite number of sides. Additionally, the protrusions may be conicalprotrusions with truncated cone or domed outermost ends.

[0065] When designing a three-dimensional structure, the desiredphysical properties of the resulting structure will dictate the size,geometrical shape, and spacing of the three-dimensional topographicalfeatures as well as the choice of materials and forming techniques. Forexample, deformable three-dimensional protrusions will typically exhibitvarying degrees of deformabilty, particularly crushability, dependingupon their cross-sectional shape and average equivalent diameter. Thebending modulus and/or flexibility of the overall web will depend uponthe relative proportion of two-dimensional material betweenthree-dimensional protrusions.

[0066] When describing properties of three-dimensional structures ofnon-uniform, particularly non-circular, shapes and non-uniform spacing,it is often useful to utilize “average” quantities and/or “equivalent”quantities. For example, in terms of characterizing linear distancerelationships between three-dimensional protrusions in a two-dimensionalpattern, where spacings on a center-to-center basis or on an individualspacing basis, an “average” spacing term may be useful to characterizethe resulting structure. Other quantities that could be described interms of averages would include the proportion of surface area occupiedby protrusions, protrusion area, protrusion circumference, protrusiondiameter, etc. For other dimensions such as protrusion circumference andprotrusion diameter, an approximation can be made for protrusions whichare non-circular by constructing a hypothetical equivalent diameter asis often done in hydraulic contexts.

[0067] The three-dimensional shape of individual protrusions is believedto play a role in determining both the physical properties of individualprotrusions as well as overall web properties. Of particular interestfor certain applications is crush resistance of protrusions (i.e., theirability to resist a deformation by crushing and/or inverting in adirection substantially perpendicular to the plane of the material).Without wishing to be bound by theory, it is presently believed that thecrush resistance of a given protrusion depends upon the crush strengthsof the individual panel segments which define each facet along theperimeter of the protrusion. The panel segment with the lowest crushstrength limits the crush strength of the protrusion, much as theweakest link defines the strength of a length of chain.

[0068] Buckling strengths of individual panels can be increased byintroducing curvature to the panel in a plane perpendicular to the crushdirection, with buckling strength increasing with decreasing radius ofcurvature. Buckling strengths of individual panels may also be increasedby decreasing the width of the panel for a constant height (i.e.,decreasing the aspect ratio). In the case of non-curvilinear protrusionshaving a finite number of sides of substantially planar shape,application of these principles suggests that protrusions will exhibitgenerally greater crush resistance as the equality in side length andincluded angles increases by minimizing the “weakest link” effect.Accordingly, a protrusion with one side substantially longer than theothers will be limited in crush strength by the buckling behavior ofthat longest side. Therefore, crush strength for a given perimeter andgiven wall thickness would be greater for a protrusion having a greaternumber of smaller sides and would maximize its crush resistance byhaving the sides of substantially similar dimensions to minimize theweakest link effect.

[0069] It should be noted that the foregoing discussion assumesgeometric replication of three-dimensional structures from a formingstructure of geometrically-sound shapes. “Real world” effects such ascurvature, degree of moldability, radius of corners, etc. should betaken into account with regard to ultimately exhibited physicalproperties.

[0070] The use of an interlocking network of frustums provides somesense of uniformity to the overall web structure, which aids in thecontrol and design of overall web properties such as web stretch,tensile strength, roll profile and thickness, etc., while maintainingthe desired degree of amorphousness in the pattern. In addition, whenutilized as a base structure for application of an adhesive or otheractive substance as described in the above-referenced U.S. Pat. No.5,662,758, the use of an interlocking polygonal base pattern for theprotrusions provides a controllable width and spacing of the valleysbetween the protrusions so that the area available for contact of theactive agent with a target surface may be tailored. The use of externalpolygonal bases from which the sides of the frustums extend upwardlyalso add a degree of predictability and uniformity to the collapse ofthe protrusions under compressive forces and also improves the releaseproperties of the formed material from the corresponding formingstructure.

[0071] The use of polygons having a finite number of sides in theamorphous pattern arranged in an interlocking relationship also providesan advantage over structures employing circular or nearly-circularshapes. Patterns such as arrays employing closely-packed circles arelimited in terms of the amount of area the circles can occupy relativeto the non-circled area between adjacent circles. More specifically,even in a pattern where adjacent circles touch at their point oftangency there will still be a given amount of space “trapped” at the“corners” between consecutive points of tangency. Accordingly, evenamorphous patterns of circular shapes are limited in terms of how littlenon-circle area can be designed into the structure. Conversely,interlocking polygonal shapes with finite numbers of sides (i.e., noshapes with curvilinear sides) can be designed so as to pack closelytogether and in the limiting sense can be packed such that adjacentsides of adjacent polygons can be in contact along their entire lengthsuch that there is no “trapped” free space between corners. Suchpatterns therefore open up the entire possible range of polygon areafrom nearly 0% to nearly 100%, which may be particularly desirable forcertain applications where the low end of free space becomes importantfor functionality.

[0072] Any suitable method may be utilized to design the interlockingpolygonal arrangement of hollow frustums which provides suitable designcapability in terms of desirable protrusion size, shape, taper, spacing,repeat distance, etc. Even manual methods of design may be utilized.Such pattern may be imparted to the starting web material in anysuitable fashion, including manual methods and methods of individuallycustom-forming the protrusions.

[0073] However, in accordance with the present invention, an expeditiousmethod of designing and forming such protrusions has been developedwhich permits the precise tailoring of desirable protrusion size, shape,taper, and spacing within an amorphous pattern, repeat distance of theamorphous pattern, etc. as well as the continuous formation of webscontaining such protrusions in an automated process.

[0074] A totally random pattern of three-dimensional hollow protrusionsin a web would, in theory, never exhibit face-to-back nesting since theshape and alignment of each frustum would be unique. However, the designof such a totally random pattern would be very time-consuming andcomplex proposition, as would be the method of manufacturing a suitableforming structure. In accordance with the present invention, thenon-nesting attributes may be obtained by designing patterns orstructures where the relationship of adjacent cells or structures to oneanother is specified, as is the overall geometrical character of thecells or structures, but wherein the precise size, shape, andorientation of the cells or structures is non-uniform and non-repeating.The term “non-repeating”, as utilized herein, is intended to refer topatterns or structures where an identical structure or shape is notpresent at any two locations within a defined area of interest. Whilethere may be more than one protrusion of a given size and shape withinthe pattern or area of interest, the presence of other protrusionsaround them of non-uniform size and shape virtually eliminates thepossibility of an identical grouping of protrusions being present atmultiple locations. Said differently, the pattern of protrusions isnon-uniform throughout the area of interest such that no grouping ofprotrusions within the overall pattern will be the same as any otherlike grouping of protrusions. The beam strength of the three-dimensionalsheet material will prevent significant nesting of any region ofmaterial surrounding a given protrusion even in the event that thatprotrusion finds itself superimposed over a single matching depressionsince the protrusions surrounding the single protrusion of interest willdiffer in size, shape, and resultant center-to-center spacing from thosesurrounding the other protrusion/depression.

[0075] Professor Davies of the University of Manchester has beenstudying porous cellular ceramic membranes and, more particularly, hasbeen generating analytical models of such membranes to permitmathematical modeling to simulate real-world performance. This work wasdescribed in greater detail in a publication entitled “Porous cellularceramic membranes: a stochastic model to describe the structure of ananodic oxide membrane”, authored by J. Broughton and G. A. Davies, whichappeared in the Journal of Membrane Science, Vol. 106 (1995), at pp.89-101, the disclosure of which is hereby incorporated herein byreference. Other related mathematical modeling techniques are describedin greater detail in “Computing the n-dimensional Delaunay tessellationwith application to Voronoi polytopes”, authored by D. F. Watson, whichappeared in The Computer Journal, Vol. 24, No. 2 (1981), at pp. 167-172,and “Statistical Models to Describe the Structure of Porous CeramicMembranes”, authored by J. F. F. Lim, X. Jia, R. Jafferali, and G. A.Davies, which appeared in Separation Science and Technology, 28(1-3)(1993) at pp. 821-854, the disclosures of both of which are herebyincorporated herein by reference.

[0076] As part of this work, Professor Davies developed atwo-dimensional polygonal pattern based upon a constrained Voronoitessellation of 2-space. In such a method, again with reference to theabove-identified publication, nucleation points are placed in randompositions in a bounded (pre-determined) plane which are equal in numberto the number of polygons desired in the finished pattern. A computerprogram “grows” each point as a circle simultaneously and radially fromeach nucleation point at equal rates. As growth fronts from neighboringnucleation points meet, growth stops and a boundary line is formed.These boundary lines each form the edge of a polygon, with verticesformed by intersections of boundary lines.

[0077] While this theoretical background is useful in understanding howsuch patterns may be generated and the properties of such patterns,there remains the issue of performing the above numerical repetitionsstep-wise to propagate the nucleation points outwardly throughout thedesired field of interest to completion. Accordingly, to expeditiouslycarry out this process a computer program is preferably written toperform these calculations given the appropriate boundary conditions andinput parameters and deliver the desired output.

[0078] The first step in generating a pattern for making athree-dimensional forming structure is to establish the dimensions ofthe desired forming structure. For example, if it is desired toconstruct a forming structure 8 inches wide and 10 inches long, foroptionally forming into a drum or belt as well as a plate, then an X-Ycoordinate system is established with the maximum X dimension (X_(Max))being 8 inches and the maximum Y dimension (Y_(Max)) being 10 inches (orvice-versa).

[0079] After the coordinate system and maximum dimensions are specified,the next step is to determine the number of “nucleation points” whichwill become polygons corresponding to the number of protrusions desiredwithin the defined boundaries of the forming structure. This number isan integer between 0 and infinity, and should be selected with regard tothe average size and spacing of the polygons desired in the finishedpattern. Larger numbers correspond to smaller polygons, and vice-versa.A useful approach to determining the appropriate number of nucleationpoints or polygons is to compute the number of polygons of anartificial, hypothetical, uniform size and shape that would be requiredto fill the desired forming structure. Assuming common units ofmeasurement, the forming structure area (length times width) divided bythe square of the sum of the polygon diameter and the spacing betweenpolygons will yield the desired numerical value N (rounded to thenearest integer). This formula in equation form would be:$N = \frac{X_{Max}Y_{Max}}{\left( {{{polygon}\quad {size}} + {{polygon}\quad {spacing}}} \right)^{2}}$

[0080] A random number generator is required for the next step. Anysuitable random number generator known to those skilled in the art maybe utilized, including those requiring a “seed number” or utilizing anobjectively determined starting value such as chronological time. Manyrandom number generators operate to provide a number between zero andone (0-1), and the discussion hereafter assumes the use of such agenerator. A generator with differing output may also be utilized if theresult is converted to some number between zero and one or ifappropriate conversion factors are utilized.

[0081] A computer program is written to run the random number generatorthe desired number of iterations to generate as many random numbers asis required to equal twice the desired number of “nucleation points”calculated above. As the numbers are generated, alternate numbers aremultiplied by either the maximum X dimension or the maximum Y dimensionto generate random pairs of X and Y coordinates all having X valuesbetween zero and the maximum X dimension and Y values between zero andthe maximum Y dimension. These values are then stored as pairs of (X,Y)coordinates equal in number to the number of “nucleation points”.

[0082] If the method described in the preceding paragraph is utilized togenerate a resulting pattern, the pattern will be truly random. Thistruly random pattern will, by its nature, have a large distribution ofpolygon sizes and shapes which may be undesirable in some instances. Forexample, a large distribution of polygon sizes may lead to largevariations in web properties in various regions of the web and may leadto difficulties in forming the web depending upon the formation methodselected. In order to provide some degree of control over the degree ofrandomness associated with the generation of “nucleation point”locations, a control factor or “constraint” is chosen and referred tohereafter as β (beta). The constraint limits the proximity ofneighboring nucleation point locations through the introduction of anexclusion distance, E, which represents the minimum distance between anytwo adjacent nucleation points. The exclusion distance E is computed asfollows: $E = \frac{2\beta}{\sqrt{\lambda\pi}}$

[0083] where λ (lambda) is the number density of points (points per unitarea) and β ranges from 0 to 1.

[0084] To implement the control of the “degree of randomness”, the firstnucleation point is placed as described above. β is then selected, and Eis calculated from the above equation. Note that β, and thus E, willremain constant throughout the placement of nucleation points. For everysubsequent nucleation point (X,Y) coordinate that is generated, thedistance from this point is computed to every other nucleation pointthat has already been placed. If this distance is less than E for anypoint, the newly-generated (X,Y) coordinates are deleted and a new setis generated. This process is repeated until all N points have beensuccessfully placed. If β=0, then the exclusion distance is zero, andthe pattern will be truly random. If β=1, the exclusion distance isequal to the nearest neighbor distance for a hexagonally close-packedarray. Selecting β between 0 and 1 allows control over the “degree ofrandomness” between these two extremes.

[0085] Once the complete set of nucleation points are computed andstored, a Delaunay triangulation is performed as the precursor step togenerating the finished polygonal pattern. The use of a Delaunaytriangulation in this process constitutes a simpler but mathematicallyequivalent alternative to iteratively “growing” the polygons from thenucleation points simultaneously as circles, as described in thetheoretical model above. The theme behind performing the triangulationis to generate sets of three nucleation points forming triangles, suchthat a circle constructed to pass through those three points will notinclude any other nucleation points within the circle. To perform theDelaunay triangulation, a computer program is written to assemble everypossible combination of three nucleation points, with each nucleationpoint being assigned a unique number (integer) merely for identificationpurposes. The radius and center point coordinates are then calculatedfor a circle passing through each set of three triangularly-arrangedpoints. The coordinate locations of each nucleation point not used todefine the particular triangle are then compared with the coordinates ofthe circle (radius and center point) to determine whether any of theother nucleation points fall within the circle of the three points ofinterest. If the constructed circle for those three points passes thetest (no other nucleation points falling within the circle), then thethree point numbers, their X and Y coordinates, the radius of thecircle, and the X and Y coordinates of the circle center are stored. Ifthe constructed circle for those three points fails the test, no resultsare saved and the calculation progresses to the next set of threepoints.

[0086] Once the Delaunay triangulation has been completed, a Voronoitessellation of 2-space is then performed to generate the finishedpolygons. To accomplish the tessellation, each nucleation point saved asbeing a vertex of a Delaunay triangle forms the center of a polygon. Theoutline of the polygon is then constructed by sequentially connectingthe center points of the circumscribed circles of each of the Delaunaytriangles, which include that vertex, sequentially in clockwise fashion.Saving these circle center points in a repetitive order such asclockwise enables the coordinates of the vertices of each polygon to bestored sequentially throughout the field of nucleation points. Ingenerating the polygons, a comparison is made such that any trianglevertices at the boundaries of the pattern are omitted from thecalculation since they will not define a complete polygon.

[0087] Once a finished pattern of interlocking polygonal two-dimensionalshapes is generated, in accordance with the present invention such anetwork of interlocking shapes is utilized as the design for one websurface of a web of material with the pattern defining the shapes of thebases of the three-dimensional, hollow protrusions formed from theinitially planar web of starting material. In order to accomplish thisformation of protrusions from an initially planar web of startingmaterial, a suitable forming structure comprising a negative of thedesired finished three-dimensional structure is created which thestarting material is caused to conform to by exerting suitable forcessufficient to permanently deform the starting material.

[0088] From the completed data file of polygon vertex coordinates, aphysical output such as a line drawing may be made of the finishedpattern of polygons. This pattern may be utilized in conventionalfashion as the input pattern for a metal screen etching process to forma three-dimensional forming structure suitable for forming the materialsof the present invention. If a greater spacing between the polygons isdesired, a computer program can be written to add one or more parallellines to each polygon side to increase their width (and hence decreasethe size of the polygons a corresponding amount).

[0089] Preferably, the computer program described above provides as itsoutput a computer graphic (.TIFF) file. From this data file, aphotographic negative can be made for use in a photoetching process toetch negative impressions into a base material to correspond to thedesired frustum polygonal shapes in the finished web of material.Alternatively, depending upon the desired process of generating thenegative forming structure for forming the finished web, it may bedesirable to tailor the output of the computer program to delivercoordinate points, etc. of the polygonal recesses, such as would proveuseful if a mechanical process were to be utilized. In addition, if itwere desirable to form a male pattern the computer output could betailored to provide the desired information to the forming apparatus tothe extent it may differ than for a negative (female) pattern.

[0090] To provide further illustration of the effect of increasinglevels of constraint obtained by various values of β, an exemplary βvalue of 0.25 (i.e., in the lower end of the range of 0 to 1) yields amuch greater variation in the center-to-center spacing of the nucleationpoints and thus the resulting polygons than does an exemplary β, valueof 0.75 (i.e., near the higher end of the range of 0 to 1). Such degreeof variation in center-to-center spacing also in the geometrical sensetranslates into a corresponding degree of variation in number of sidesin the resulting polygons as well as polygon size, the effects of whichwere discussed above. In order to produce the desired level ofamorphousness in the resulting pattern of polygons, the value presentlypreferred for β is 0.75, but this value may of course be tailored asrequired to suit a particular application.

[0091] The polygon area distribution decreases as the constraint (β) isincreased. Said differently, the less constrained pattern exhibits abroader range of polygon sizes than the more constrained pattern.Moreover, for a given sample “test box” drawn within the pattern, achange in the area of the test box affects the range of % polygon arefor a given pattern. As the area of the test box decreases, thevariability in % polygon area increases. Conversely, as the area of thetest box increases, beyond a certain point the % polygon area remainsconstant throughout the pattern. The more constrained material of(larger β) displays a much narrower range of % polygon area andconverges to a constant % polygon area at a smaller test box size than aless constrained material. Further, for consistency in physicalproperties throughout the web more constrained tessellations exhibitless variation in aerial density, i.e., the localized number ofprotrusions and corresponding protrusions wells, per unit area.

[0092] Based upon these observations, it would be apparent that apredictable level of consistency may be designed into the patternsgenerated according to the preferred method of the present inventioneven though amorphousness within the pattern is preserved. Accordingly,three-dimensional, amorphous-patterned, nesting-resistant materials maybe formed with statistically-predictable geometric and physical materialproperties.

[0093] Referring once again to the drawings, and more particularly toFIG. 2, there is shown a plan view of a representativethree-dimensional, nesting-resistant sheet material suitable for use asa storage wrap material of the present invention, which is generallyindicated as 10. FIG. 2 represents an amorphous two-dimensional patterngenerated by the above-described method utilizing a constraint factor of0.75. Material 10 has a plurality of non-uniformly shaped and sized,preferably hollow, protrusions 12, surrounded by spaces or valleys 14therebetween, which are preferably interconnected to form a continuousnetwork of spaces within the amorphous pattern. FIG. 2 also shows adimension A, which represents the width of spaces 14, measured as thesubstantially perpendicular distance between adjacent, substantiallyparallel walls at the base of the protrusions. In a preferredembodiment, the width of spaces 14 is preferably substantially constantthroughout the pattern of protrusions.

[0094] Preferred protrusions 12 of the present invention are generatedwith non-uniform size and shape so that material 10 may be wound onto aroll without nesting occurring between layers of material within theroll. The nesting-resistant feature is achieved because the amorphouspattern of the protrusions, as discussed above, limits the ability ofthe face of one layer to align with the back of another layer wherebythe protrusions of one layer enter the depressions formed behind eachprotrusion in an adjacent layer. The benefit of narrow constant-widthspaces between protrusions is that protrusions 12 cannot also enterspaces 14 when layers of material 10 are placed face to face.

[0095] Protrusions 14 are preferably spaced center to center an averagedistance of approximately two protrusion base diameters or closer, inorder to minimize the volume of valleys between protrusions and hencethe amount of substance located between them. For applications where itis intended that the protrusions be deformable, the protrusions 14preferably have heights which are less than their diameters, so thatwhen they deform, they deform by substantially inverting and/or crushingalong an axis which is substantially perpendicular to a plane of thematerial. This protrusion shape and mode of deforming discouragesprotrusions 14 from folding over in a direction parallel to a plane ofthe material so that the protrusions cannot block a substance present inthe valley between them from contact with a target surface.

[0096]FIG. 3 depicts a fragmentary elevational cross-section of material10 taken at a location where a complete protrusion 12 and both adjoiningspaces or valleys 14 can be seen in cross-section. In this view, theupper surface of the web which faces the viewer of FIG. 2, and whichincludes the projecting portions of the protrusions 12, is identifiedwith the numeral 15, and is referred to hereafter as the male side ofthe material. Correspondingly, the lower surface of the web facing awayfrom the viewer of FIG. 2, which includes the openings of the hollowportions of the protrusions 12, is identified with the numeral 17, andis referred to hereafter as the female side of the material.

[0097]FIG. 3 shows a substance 16 added to spaces 14, as well as to thehollow underside of the protrusions 12, in accordance with the teachingsof commonly-assigned, co-pending, concurrently-filed U.S. Pat. No.5,871,607, issued to Hamilton et al. on Feb. 16, 1999, herebyincorporated herein by reference. Substance 16 partially fills thespaces 14 so that an outer surface of protrusions 12 remain external tothe surface level of substance 16 such that the protrusions prevent thesubstance 16 on the male side of the material from making contact withexternal surfaces. With regard to the male side of the material,substance 16 partially fills the hollow protrusions such that thereverse side of the valleys or spaces between respective protrusionsserves an analogous function in preventing substance 16 within theprotrusions from making contact with external surfaces. Substanceswithin different sides of the material 10 and/or within differentgeometrically-distinct zones within a side of material 10 need not bethe same substance and could in fact be distinctly different substancesserving distinctly different functions.

[0098] “Substance” is defined in this invention as any material capableof being held in open valleys and/or depressions of a three dimensionalstructure. In the present invention, the term “substance” can mean aflowable substance which is substantially non-flowing prior to deliveryto a target surface. “Substance” can also mean a material which doesn'tflow at all, such as a fibrous or other interlocking material.“Substance” may mean a fluid or a solid. Adhesives, electrostatics,mechanical interlocking, capillary attraction, surface adsorption, andfriction, for example, may be used to hold the substances in the valleysand/or depressions. The substances may be permanently held in thevalleys and/or depressions, or the substances may be intended to bereleased therefrom when exposed to contact with external surfaces orwhen the three dimensional structure is deformed, heated, or otherwiseactivated. Of current interest in the present invention includesubstances such as gels, pastes, foams, powders, agglomerated particles,prills, microencapsulated liquids, waxes, suspensions, liquids, andcombinations thereof.

[0099] The spaces in the three-dimensional structure of the presentinvention are normally open; therefore it is desirable to havesubstances stay in place and not run out of the structure without anactivation step. The activation step of the present invention ispreferably deformation of the three-dimensional structure bycompression. However, an activation step to cause substance to flowcould be heating the material to above room temperature or cooling itbelow room temperature. Or it could include providing forces excessiveof the earth's gravity. It could also include other deforming forces,such as tensile forces and combinations of these activation phenomena.

[0100] The term “deformable material” is intended to include foils,polymer sheets, cloth, wovens or nonwovens, paper, cellulose fibersheets, co-extrusions, laminates, and combinations thereof. Theproperties of a selected deformable material can include, though are notrestricted to, combinations or degrees of being: porous, non-porous,microporous, gas or liquid permeable, non-permeable, hydrophilic,hydrophobic, hydroscopic, oleophilic, oleophobic, high critical surfacetension, low critical surface tension, surface pre-textured, elasticallyyieldable, plastically yieldable, electrically conductive, andelectrically non-conductive. Such materials can be homogeneous orcomposition combinations.

[0101] In a particularly preferred embodiment, protrusions 14 have anaverage base diameter of about 0.015 inches (0.038 cm) to about 0.030inches (0.076 cm), and more preferably about 0.025 inches (0.064 cm).They also have an average center-to-center spacing of from 0.03 inches(0.08 cm) to 0.06 inches (0.15 cm), and more preferably about 0.05inches (0.13 cm) spacing. This results in a high number density ofprotrusions. The more protrusions per unit area, the thinner the pieceof material and protrusion walls can be in order to resist a givendeformation force. In a preferred embodiment the number of protrusionsper square inch exceeds 200 and the protrusions occupy from about 30% toabout 70% of the protrusion side of the piece of material. They have aprotrusion height of about 0.004 inches (0.010 cm) to 0.012 inches(0.030 cm), and more preferably about 0.006 inches (0.015 cm) height.The preferred material is 0.0003 inch (0.0076 mm) nominal thickness highdensity polyethylene (HDPE).

[0102] For fabrication of an adhesive-containing, three-dimensional,nesting-resistant sheet material, a preferred layer of substance 16 ispreferably a latex pressure sensitive adhesive about 0.001 inch (0.025mm) thick. Even more preferably, layer of substance 16 may be about0.0005 inch (0.013 mm) thick layer to about 0.002 inch (0.051 mm) thicklayer of hot melt adhesive, specification no. Fuller HL-2115X, made byH. B. Fuller Co. of Vadnais Heights, Minn. Any adhesive can be usedwhich suits the needs of the material application. Adhesives may berefastenable, releasable, permanent, or otherwise. The size and spacingof protrusions is preferably selected to provide a continuous adhesivepath surrounding protrusions so that air-tight seals may be made with atarget surface.

[0103] Film materials may be made from homogeneous resins or blendsthereof. Single or multiple layers within the film structure arecontemplated, whether co-extruded, extrusion-coated, laminated orcombined by other known means. The key attribute of the film material isthat it be formable to produce protrusions and valleys. Useful resinsinclude polyethylene, polypropylene, PET, PVC, PVDC, latex structures,nylon, etc. Polyolefins are generally preferred due to their lower costand ease of forming. Preferred material gauges are about 0.0001 inches(0.0025 mm) to about 0.010 inches (0.25 mm). More preferred gauges arefrom about 0.0002 inches (0.005 mm) to about 0.002 inches (0.051 mm).Even more preferred gauges are from about 0.0003 inches (0.0076 mm) toabout 0.001 inches (0.025 mm).

[0104] Providing a film modulus of elasticity sufficiently high tominimize film stretch during use is beneficial to sealing material 10 toa target surface. Stretched film results in residual forces parallel tothe plane of adhesive contact, which may cause a weak adhesive bond tobreak. The larger and more closely spaced the protrusions, the greaterthe likelihood of stretch occurring in a given film. Although elasticityin material 10 is believed to be undesirable for use as a container wrapwhich seals to a container, there are potentially many other uses for anelastic material containing a pattern of substance. Reducing theprotrusion spacing to the closest possible spacing which ismanufacturable may increase material stretch, but it may be beneficialin reducing the volume of substance between protrusions. Differentapplications for the formed material of the present invention willdictate ideal size and density of protrusions, as well as the selectionof the substances used therewith.

[0105] The material property “beam strength” of the three-dimensionalsheet material was mentioned above in terms of the beam strengthpreventing significant nesting of any region of material surrounding agiven protrusion even in the event that that protrusion finds itselfsuperimposed over a single matching or larger depression of compatibleshape since the protrusions surrounding the single protrusion ofinterest will differ in size, shape, and spacing from those surroundingthe other protrusion/depression. Beam strength is thus an importantfactor to consider when selecting the material type and thickness, aswell as the density and pattern of protrusions. It has been observedthat in general larger numbers of smaller protrusions provide a greaterlevel of beam strength for a given material type and thickness than asmaller number of larger protrusions. Said differently, thinner and moreconformable materials may be utilized and still realize the non-nestingadvantages of the present invention through the use of an amorphouspattern having generally comparatively small, comparatively high numberdensity protrusions.

[0106] It is believed that the protrusion size, shape and spacing, theweb material properties such as flexural modulus, material stiffness,material thickness, hardness, deflection temperature as well as theforming process determine the strength of the protrusion. The formingprocess is important in polymer films for example, since “cold forming”or embossing generates residual stresses and different wall thicknessdistributions than that produced by thermoforming at elevatedtemperatures. For some applications it is desirable to provide astiffness (deformation resistance) which is sufficient to withstand apressure of at least 0.1 pounds per square inch (0.69 kPa) withoutsubstantially deforming protrusions to where the substance contacts anexternal surface. An example of this requirement would be the need towind the web onto a roll for transport and/or dispensing. Even with verylow in-wound pressures of 0.1 pounds per square inch (0.69 kPa), aresidual in-wound pressure in the interior of the roll may deformprotrusions in the web sufficiently to bring the overlaying web layersinto contact with the substance. A “threshold” protrusion stiffness isrequired to prevent this winding damage from occurring. Similarly, whenthe web is stored or dispensed as discrete sheets, this “threshold”stiffness is required to prevent premature activation of the product dueto the weight of overlaying layers of sheets or other forces, such asforces induced by shipping vibrations, mishandling, dropping and thelike.

[0107] Deformation mode and force can be influenced by the sidewallthickness profile to provide more desired results. A protrusion'ssidewall connects the outermost portion of the protrusion to theunformed material adjacent to base perimeter of the protrusion. Thesidewall as defined may also contain a peripheral region substantiallywithin the outermost portion which is substantially thinner than theinterior region of the outermost portion. Protrusions where at least aportion of the sidewalls are substantially thinner than the unformedmaterial adjacent to the base perimeter are believed preferred fordeformation by the user. Sidewalls that are also substantially thinnerin at least a portion of the sidewall as compared to the material at theoutermost portion of the protrusion also beneficially bias thedeformation to occur primarily within the sidewall structure.

[0108] In structures containing relatively small protrusions, as foundin high number density protrusion patterns, such thinner sidewall gaugescan be particularly useful.

[0109] Protrusions 12 have sidewalls 22, which become thinned whenprotrusions 12 are formed, to help ensure that protrusions 12 deform asintended. High density polyethylene is preferred over low densitypolyethylene because the former can be made thinner for the sameprotrusion deform strength and because once deformed, HDPE protrusionsdo not tend to rebound toward their undeformed initial configuration asdo the LDPE protrusions.

[0110] Protrusions 12 preferably have a convex polygonal base shape, theformation of which is described hereinafter. By convex polygonal shape,it is meant that the bases of the protrusions have multiple (three ormore) linear sides, which form no externally measured angle of less than180° with any adjacent side. Of course, alternative base shapes areequally useful. However, the preferred base shape is believed to be mosteasily generated. Polygons preferably interlock in the plane of thelower or female surface 17, as in a tessellation, to provide constantwidth spacing between them. The width A of spaces 14 may be selecteddepending upon the volume of substance desired between protrusions.Preferably width A is always less than the minimum protrusion dimensionof any of plurality of protrusions 12. The area occupied by plurality ofprotrusions 12 is preferably from about 30% to about 70%, morepreferably about 50%, of the available area of sheet of material 10, asmeasured parallel to plane 20.

[0111] FIGS. 4-6 disclose a suitable method and apparatus for makingmaterial 10, the method generally indicated as 30. Method 30 isrepresentative and may be modified or tailored to suit a particularsize, composition, etc. of the resulting material 10. Method 30 utilizesa forming surface 32, which is preferably a three-dimensional screenhaving recesses 34 and lands 36 between recesses 34. Such a formingstructure or forming structure would constitute a female-type formingstructure which, in use, would form corresponding male protrusions inthe structure-contacting side of the formed material. Alternatively,forming surface 32 could comprise a three-dimensional forming structureof the male variety by having raised pins 34 of the desired polygonalshape having recesses 36 between and around the pins 34. In use, such aforming structure would form corresponding female depressions in thestructure-contacting side of the formed material.

[0112] More particularly, FIG. 4 depicts a forming surface which couldbe utilized to form a corresponding three-dimensional material 10 suchas depicted in FIG. 2. When a material 10 is thermoformed over formingsurface 32, protrusions 12 are preferably formed by drawing them intorecesses 34 with vacuum when material 10 is heated to a softeningtemperature, and then maintaining protrusions 12 drawn into recesses 34while material 10 cools to a solidification temperature. In this method,lands 36 define the bases of spaces 14 between protrusions 12.Protrusions 12 are preferably formed with sidewalls 22 being as nearlyperpendicular to plane 20 as possible, but with some taper beingtypical. Outermost ends of protrusions 12 may domed or more truncated inshape so as to form frustums of the corresponding polygonal shape.

[0113] Material 10 may be vacuum thermoformed, embossed, or hydroformed,or formed by other forming means commonly known in the art forpermanently deforming thin materials.

[0114]FIG. 4 shows a preferred forming screen 32 comprisinginterconnected lands 36 surrounding polygonal recesses 34. Lands 36 arepreferably made of stainless steel and coated with a release agent. Mostpreferably, screen 32 is made into a continuous belt 38, as shown inFIG. 6. Alternatively, screen 32 could be utilized in flat plate-likeform or formed into a rigid drum. FIG. 5 depicts a partialcross-sectional view of forming screen 32 taken at a location whichdepicts a cross-section through two consecutive lands. Lands 36 have adimension B which represents the land width, which is preferablyconstant as measured between substantially parallel adjacent land edges,and a dimension T which represents screen thickness.

[0115] The amorphous pattern of the forming screen is preferablygenerated in accordance with the method described above.

[0116] Methods of production can influence the sidewall thicknessprofile such as in the use of a forming screen with essentially straightscreen walls which define the forming screen hole. Such a process allowsfor substantially thinner sidewall thickness since the protrusion isfreely drawn from the base perimeter into the forming screen recess tothe point of contact with the internal backup screen. The internalbackup screen's purpose is to prevent further drawing of the protrusion.This approach yields a more varied gauge profile within the sidewalls.

[0117] It has been discovered while reducing to practice the presentinvention that when using hot melt adhesive for the substance,thermoforming behaves differently than when other substances areprocessed. The difference is that protrusions, which are formed when hotmelt adhesive has been applied to the forming surface, tend to exhibitmore thinning in their sidewalls. It is believed that the hot meltadhesive cools and solidifies when contacting the metal forming surfaceand thereby prevents web material in contact with the adhesive frombeing drawn into the recesses, so that uniform thickness valleys result.With other substances, such as latex adhesive, less thinning ofprotrusion sidewalls occurs, presumably because some of the web materialin contact with the adhesive on the lands or pin tops of the formingsurface flows into the recesses during thermoforming.

[0118]FIG. 6 shows a suitable and presently preferred method andapparatus for making a material such as material 10 of the presentinvention, which is generally indicated as 180. The formed material ispreferably transparent or translucent, so that it may be accuratelypositioned before being deformed. Transparency, however, introduces anew problem of determining on which side of the three-dimensionalstructure the substance is located, in order to know which side to placeagainst a target surface. Substance side identification can be solved byplacing indicia on the surface of the three dimensional structure, bycoloring the substance a different tint than the three dimensionalstructure, or by providing a laminated material structure of differenttints, for example. In the case of labels, transparency may not beneeded since material edges may be used for proper positioning.

[0119] Micro-texturing the material during forming may also be useful,such as in producing a distinction between one side of the material andthe other side. Micro-texturing of the outermost surface features of thethree dimensional structure may be achieved in the present invention,for example, by drawing the piece of material into forming screenrecesses and against a micro-textured surface, such as a vacuum drumhaving tiny apertures therein.

[0120] Forming screen 181 is threaded over idler pulley 182 and a drivenvacuum roll 184. Forming screen 181 is preferably a 0.005 inch (0.013cm) thick, 12.5 inch (31.8 cm) wide, 6 foot (183 cm) circumferencestainless steel belt, having the desired protrusion pattern etched asrecesses in the belt. Covering the outer surface of vacuum roll 184 is a195 mesh seamless nickel screen having a diameter of 8.63 inches (21.9cm), which serves as a porous backing surface for forming screen 181.

[0121] For producing a pressure sensitive adhesive containing material,a substance 186, preferably hot melt adhesive, is coated onto formingscreen 181 by a substance applicator 188 while forming screen 181travels at about 20 feet (610 cm) per minute. A material 190, forexample, a HDPE film web about 0.0005 inches (0.0013 cm) thick, isbrought into contact with the substance-coated forming screen atmaterial infeed idler roll 192. Hot air at approximately 600° F. (316°C.) and flowing at approximately 11.25 SCFM (0.32 cubic meters/minute)is directed radially at material 190 by a hot air source 194 as thematerial passes over vacuum roll 184 and as vacuum is applied to formingscreen 181 through vacuum roll 184 via fixed vacuum manifold 196 from avacuum source (not shown). A vacuum of approximately 12 inches ofmercury (40.6 kPa) is applied as the material is heated by hot airsource 194. A formed, substance coated material 198 is stripped fromforming screen 181 at stripping roll 200.

[0122] Stainless steel forming screen 181 is a fabricated, seamed belt.It is fabricated in several steps. The recess pattern is preferablydeveloped by a computer program according to the method described aboveand is preferably printed onto a transparency to provide a photomask forphotoetching. The photomask is used to create etched and non-etchedareas. The etched material is typically stainless steel, but it may alsobe brass, aluminum, copper, magnesium, and other materials includingalloys. Methods of making metal screens by photoetching are described inmore detail in commonly owned U.S. Pat. No. 4,342,314 to Radel andThompson, U.S. Pat. No. 4,508,256 to Radel et al., and U.S. Pat. No.4,509,908 to Mullane, Jr., the disclosures of which are herebyincorporated herein by reference.

[0123] Additionally, the recess pattern may be etched intophotosensitive polymers instead of metals. Examples are described alongwith a methods of making polymer forming screens in commonly owned U.S.Pat. No. 4,514,345 to Johnson et al., U.S. Pat. No. 5,098,522 toSmurkoski et al., U.S. Pat. Nos. 4,528,239 to Trokhan, and 5,245,025 toTrokhan, the disclosures of which are hereby incorporated herein byreference.

[0124] Next, the forming screen is converted into a continuous belt bybutt welding the ends together, using either laser or electron beamwelding. This produces a nearly undetectable seam, which is needed tominimize disruptions in the recess pattern. The final step is coatingthe endless belt with a low critical surface tension (non-stick)coating, such as a Series 21000 proprietary release coating made by andapplied by Plasma Coatings of TN, Inc., located in Memphis, Tenn. It isbelieved that this coating is primarily an organo-silicone epoxy. Asapplied to a stainless steel forming screen used in the methods of thepresent invention, this coating provides a critical surface tension ofabout 18 dynes/cm. Other materials which may prove suitable forproviding reduced critical surface tension include paraffins, silicones,PTFE's, and the like. This coating allows the formed material to beremoved from the belt without undue stretching or tearing.

[0125] A belt forming screen is believed advantageous to a flat plate ora drum forming screen because a belt enables screen patterns and patternlengths to be changed more easily and larger patterns may be usedwithout having massive rotating members. However, depending upon thedesired quantity and dimensions of the material 10 to be formed it maybe equally suitable to fabricate the forming structure as a flat plateor rigid drum, and/or other forming structures and methods known in theart.

[0126] Because the same common forming screen is used to transfer thesubstance to the material as is used to form the protrusions, thesubstance pattern is conveniently registered with the protrusions. Inthe preferred embodiment, the top surface of forming screen 32 iscontinuous except for recesses 34; thus, the substance pattern istotally interconnected in this configuration. However, if adiscontinuous pattern of substance were coated onto forming screen 32, adiscontinuous substance pattern between protrusions would result.

[0127] In accordance with the preferred method of manufacturing thethree-dimensional, nesting-resistant sheet material 10, thethree-dimensional protrusions are unitarily formed from the sheet ofdeformable material itself and are hollow structures with depressions inone side which preferably each have a size and three-dimensional shapecorresponding substantially with the size and three-dimensional shape oftheir respective protrusion. However, it may also be desirable for someapplications to utilize solid protrusions unitarily, integrally, orseparately formed from (and applied to) the sheet of material and whichmay or may not be deformable.

[0128] In general, the present invention is a storage wrap materialwhich may take the form of a three-dimensional sheet material which isactivated by applying a compressive force so that the structurecollapses to expose an adhesive to contact with external surface(s).However, the scope of the invention also applies to storage wrapmaterials which are activatible by means other than compression. Forexample, the inventors have found that a tensile force applied to thesame three-dimensional structure can cause it to plastically deformlongitudinally and thereby contract in caliper or thickness to similarlyexpose or release substance. It is believed that under sufficienttension, the material between protrusions deforms in response to forcesin the plane of the material and that protrusions are thereby elongatedin the same direction. When the protrusions are elongated, they arereduced in height. With enough elongation the protrusions are reduced inheight to where the substances between them, in them, or both areexposed.

[0129] For a one inch wide strip of material 10, made from 0.0003 inch(0.0076 mm) thick HDPE and formed to have protrusions of 0.006 inches(0.152 mm) height and 0.030 inches (0.762 mm) diameter, spaced 0.045inches (1.14 mm) apart, the tensile force found necessary to causeprotrusions to expose a 0.001 inch (0.025 mm) thick coating of adhesivein the valleys between protrusions is approximately 0.80 pounds (0.36kg) per inch of strip width.

[0130] A combination of compression and tensile forces may be applied tothe material of the present invention in order to expose a substancefrom within the three-dimensional structure. Although in a preferredembodiment of the present invention, the tensile force necessary toachieve sufficient deformation of said three-dimensional structure inorder to expose substance to an external surface is significantlygreater than a compressive force to achieve the same result, a structuremay be designed which is more easily deformed by a tensile force appliedin a specific planar direction. For example, a structure may haveparallel waves instead of protrusions and the waves may be easilyflattened by stretching the structure perpendicular to the waves but inthe plane of the waves. Tensile responsive structures and the principlesbehind them are disclosed in commonly-assigned U.S. Pat. No. 5,518,801to Chappell et al., the disclosure of which is hereby incorporatedherein by reference.

[0131] In another example, heat could be applied to cause the samestructure made of shrinkable film to reduce in thickness to similarlyrelease or expose the substance.

[0132] As described herein, different substances can be deposited on theopposing faces of the formed material. Multiple substances can belocated on the same face of the material either geometrically spacedfrom each other or commingled. Substances can be partially layered. Anexample is a layer of adhesive adjacent to the material surface with asolid particulate adhered to the exposed side of the adhesive layer. Inaddition, it is contemplated that it may be desirable for certainapplications to have protrusions extending outwardly from both sides ofthe formed material, such that both sides are active sides withdeformable protrusions.

[0133] A pattern of protrusions can be superimposed either on a similardimensional scale or on a different dimensional scale such as a singleor multiple “microprotrusion” pattern located on the tops of otherlarger protrusions.

[0134] Additional details of the process of FIG. 6, as well asadditional details regarding three-dimensional materials described abovemay be found in the aforementioned and incorporated U.S. Pat. No.5,871,607.

[0135] While under some circumstances it may be acceptable or desirableto design the storage wrap material so as to form a discontinuous bondpattern with itself or another target surface, such as by having anintermittent or discontinuous layer of adhesive on its active surface,it is presently preferred that the storage wrap material be designed soas to exhibit the ability to form a continuous seal or bond with itselfand with any sufficiently continuous target surface.

[0136] FIGS. 7-9 depict representative applications of interest for thestorage wrap material 10.

[0137] More particularly, FIG. 7 depicts storage wrap material 10utilized independently to form a closed container for an item 60. Foruse in this fashion, a one-sided version of storage wrap material 10 ispreferably utilized such that only one side of the material is active,although a two-sided material could also be utilized. To utilize storagewrap material 10 in this fashion, the material is wrapped or foldedaround the desired item 60 so as to leave a marginal edge extendingoutwardly beyond the maximum dimensions of the item 60. As depicted inFIG. 7, the web of storage wrap material 10 has been folded over andaround the item 60 by folding the material along a folded edge 55 andforming a fin-type seal 50 around the remaining perimeter, in thisinstance three sides, of the item 60. In this deployment, the storagewrap material 10 is bonded or adhered to itself in a face-to-faceorientation wherein both active sides of the material are in contactwith one another. Accordingly, when a user 70 activates the adhesive onat least one, and preferably both, of the overlying or overlappingportions of the material in the region of the fin seal 50 the overlyingportions are firmly adhered together to complete the enclosure of theitem 60. Alternatively, rather than folding a larger web of materialupon itself to form an enclosure, two or more discrete smaller pieces ofstorage wrap material 10 may be utilized by wrapping them over the item60 and sealing them to one another in face-to-face or face-to-backorientation.

[0138]FIG. 8 depicts another useful deployment of storage wrap material10 as the closure of a semi-enclosed, rigid or semi-rigid container 100.In the configuration of FIG. 8, a combination container structure isthus illustrated wherein the storage wrap material is adhered to the rimportion 105 of the container which circumscribes the opening 110 to forma corresponding closure for the opening. Although the storage wrapmaterial 10 would form an adequate barrier seal if only applied to thesurface of the rim 105 which is in the plane of the opening 110, asdepicted in FIG. 8 the storage wrap material 10 may also be applied soas to effect a seal over an additional area around the periphery of therim 105 by bonding to the wall portion 115 of the container whichextends in a direction substantially normal to the plane of the opening.Effective sealing may also be accomplished by bonding the storage wrapmaterial only to the wall portion 115 of the container. Where such aclosure completely encloses the contents (not shown) of the container100, the contents are protected from the exterior environment outsidethe container and are also contained and protected from loss.

[0139] Containers such as container 100, which as shown has noprotruding structures for cooperating with storage wrap 10, arefrequently constructed of such rigid or semi-rigid materials such asmetals, glass, ceramics, plastics, or wood which have a comparativelysmooth and uniform surface. Accordingly, storage wrap material 10 inaccordance with the present invention activates to provide the desiredlevel of adhesive force in combination with such non-conforming, rigidor semi-rigid surfaces so as to effectively form a closure for suchcontainers. In addition, the storage wrap material may also be utilizedin conjunction with openings in the plane of a wall of a container aswell as openings which are formed at an end, etc. of a containersubstantially normal to adjacent wall surfaces. Such versatility is dueto the adhesive properties of the storage wrap material which, unlikedead-fold wrap materials such as waxed paper or aluminum foil, enablethe storage wrap materials of the present invention to form a suitableseal without the need to form a wrap angle around a rim, lip, or otherstructure adjacent the container opening.

[0140]FIG. 9 depicts yet another common application for storage wrap 10,wherein a discrete web of storage wrap 10 of the desired dimensions iswrapped continuously around an item 60 so as to enclose the item 60completely. Edge portions 80 of the storage wrap 10 which overly theitem and overly other portions of the storage wrap 10 are adhered tosuch other portions after activation such that they are secured insealing relationship. This mode of item enclosure is particularly usefulwhen the item has an irregular shape, such as the item 60 depicted inFIG. 9. In this mode of deployment, the storage wrap 10 is preferablyoriented with the active side facing inwardly toward the item 60 suchthat the storage wrap may be activated over the item to provideadditional security against shifting or loosening of the material.Alternatively, the storage wrap 10 could be wrapped around the item withthe active side facing outwardly if adherence to the item is notdesired. In either mode of deployment, the overlying portions 80 of thestorage wrap material 10 will be activated and adhered to one another inface-to-back relation with one of the overlying portions being activatedto provide the adhesive property and the other overlying portion beingnon-activated and hence a passive target surface.

[0141] If a two-sided activatible storage wrap material were utilized inthe above example, then either or both of the superimposed face and backportions in the overlying portions 80 could be activated to effect asealed region.

[0142] The improved storage wrap materials of the present invention maybe employed to enclose a wide variety of items, both perishable andnon-perishable. Such items may include single items within a givencontainer/package system, as well as multiple items of the same ordifferent types. Items enclosed may in fact be containers or packageswhich are themselves to be enclosed, such as a group of cartons wrappedtogether upon a pallet, for example. The items may be loosely groupedtogether within a single chamber within the container, or may besegregated within different chambers or compartments formed by thestorage wrap material itself or other features of the container.

[0143] While particular embodiments of the present invention have beenillustrated and described, it would be obvious to those skilled in theart that various other changes and modifications can be made withoutdeparting from the spirit and scope of the invention. It is thereforeintended to cover in the appended claims all such changes andmodifications that are within the scope of this invention.

What is claimed is:
 1. An improved storage wrap material comprising: a)a sheet of material comprising one or more layers, and having a first,active side and a second side, said sheet comprising a plurality ofstandoffs at a density of greater than about 200 standoffs per squareinch and spaces between the standoffs; and b) an adhesive; wherein thestandoffs are selected from the group consisting of deformablestandoffs, removable standoffs, repositionable standoffs, frangiblestandoffs, or mixtures thereof, and wherein the storage wrap material islinerless and consists of no reinforcing or supporting elements suchthat the storage wrap material is used by itself to wrap or sealmaterials.
 2. An improved storage wrap material according to claim 1wherein the adhesive is a pressure sensitive adhesive.
 3. An improvedstorage wrap material according to claim 3 wherein the sheet of materialis clingless.
 4. An improved storage wrap material according to claim 2wherein the standoffs consist of hollow, collapsible protrusions.
 5. Animproved storage wrap material according to claim 4 wherein theplurality of protrusions are in an amorpous pattern.
 6. An improvedstorage wrap material according to claim 4 wherein the plurality ofprotrusions are in a regular pattern.
 7. An improved storage wrapmaterial according to claim 1 wherein the storage wrap material isactivated by compression activation, extention activation, of thermalactivation.
 8. An improved storage wrap material according to claim 7wherein the storage wrap material is activated by a compressive force ofgreater than 0.1 psi.
 9. An improved storage wrap material according toclaim 1 wherein the adhesive partially fills the spaces between thestandoffs.